I think I'll go with the Arceus Theory. He's right, 649 is an odd number. I have a hunch that when the 1 dragon separated, one half was Reshiram, one half was Zekrom, and the energy left over fell in the form of an Ice Meteor. And from the Ice Meteor came Kyurem. That's why Kyurem looks incomplete. However, it still inherits part of the other two, considering the three came from the same dragon. I'm kinda expecting that the 650th Pokemon will be the original dragon, but i don't know what type it would be. Maybe Fire/Electric? Or maybe they introduce three types into the game? Or possibly it starts off as just a Dragon Type, but the Light Stone, Dark Stone and God Stone become normal items to put on the Dragon, and it changes type to Dragon/Fire, Dragon/Electric, or Dragon/Ice and it also changes colour? I don't know. I guess we'll have to wait and see.